1. Field of the Invention
The present invention relates to an ionic polymer membrane comprising the radiation crosslinkable poly(vinyl alcohol) and a preparation method of the same.
2. Description of the Related Art
An ionic polymer membrane is able to pass only cations or anions selectively. That is, the cationic polymer membrane can exchange only anions and the anionic polymer membrane can exchange cations alone. Such ionic polymer membranes have been applied to various fields including capacitive deionization, electrodialysis, diffusion dialysis, redox flow battery, and seawater desalination.
The commercial ionic polymer membranes are composed of hydrocarbon and fluorine based polymers added with ion-exchangeable functional groups, and the major providers are DuPont, Dow, Asahi Chemical, Asahi Glass, and Tokuyama, etc. However, the perfluorinated ionic polymer membrane has disadvantages of high production costs and low thermo-stability. The hydrocarbon based ionic polymer membrane can have advantages of high thermal stability and low production cost but their dimensional stability against moisture can be easily deteriorated with an increasing ion exchange capacity. So it is much difficult to produce the membrances with a high ion exchange capacity more than 1.5 meq./g.
Therefore, in the course of study on an ionic polymer membrane with high ion exchange capacity and high durability, the present inventors developed a flexible crosslinked ionic polymer membrane with a high ion exchange capacity and high dimensional stability that has been produced simply by mixing the commercial ionic polymer having 100 mol % of ion-exchangeable functional group with a specially synthesized double bond-introduced hydrophilic poly(vinyl alcohol) at a certain ratio, followed by irradiation, leading to the completion of this invention.